<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style>
			.box1,.box2{
				width: 300px;
				height: 300px;
			}
			.box1{
				background-color: aquamarine;
			}
			.box2{
				background-color: royalblue;
				position: absolute;
				top: 100px;/*此时父容器是浏览器，距离浏览器上部100px*/
				left: 100px;
			}
			.box2_in{
				width: 100px;
				height: 100px;
				background-color: orange;
				position: absolute;
				left: 50px;
				top: 50px;
			}
		</style>
	</head>
	<body>
		<div class="box1"></div>
		<div class="box2">
			<div class="box2_in"></div>
		</div>
		
	</body>
</html>
